Media Sharing

ABSTRACT

A method and device for distributing media from a network based content server to two or more clients participating in a burst-based service session. The method includes, following establishment of the burst-based service session, joining the content server to the session as a further participating client, sending a media grant to the content server, and delivering the requested media from the content server to the other participating clients.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for sharingmedia in a push-to-talk type session.

BACKGROUND TO THE INVENTION

Walkie-talkie type services have long proved popular amongst users whowish to communicate brief messages quickly between one another.Conventionally, such services have been provided by two-way portableradios which utilise a dedicated part of the radio spectrum, but whichonly allow users to communicate with a small group of pre-selected userswho utilise similar terminals and who are within range of the relativelyshort operating range of the radios. More recently, services have beenintroduced into the United States which piggy-back on the existingcellular telephone infrastructure. However, these services have beenproprietary in nature and have not allowed users to communicate betweendifferent operator networks.

In an attempt to broaden the use of walkie-talkie type services, anindustry grouping known as the Open Mobile Alliance(www.openmobilealliance.org) has been established with the aim ofstandardising suitable protocols which will allow inter-networkoperability for Warlike-Talkie services offered over cellular networks.The service established by the various standards is known as Push totalk Over cellular (PoC). PoC makes use of the IP Multimedia Subsystem(IMS) to handle the setting up and control of PoC sessions via PoCservers (acting as SIP ASs). PoC proposes that associated speech datawill be transported over a packet switched access network. In the caseof GSM and UMTS, this will be the general packet radio service (GPRS)access network. In other network architectures, analogous packetswitched access networks will be utilised for transporting talk data.Push to Talk services may also be offered over circuit switched accessnetworks, although this is not the preferred option. The current stateof PoC is set out in Release 1.0.

The requirements for PoC Release 2 are now being laid out. These includea requirement for sharing media content between PoC Users in a PoCSession, i.e. a push-to-watch type service. The media can be stored onthe user equipment (the “PoC Client”) or on a content server in thenetwork.

SUMMARY OF THE INVENTION

The present invention relates to push-to-talk type services such as forexample Push to talk Over cellular (PoC), as well as to related andenhanced services which are also burst based services. The term“burst-based” service is used here as a generic name for these services.

According to a first aspect of the present invention there is provided amethod of distributing media from a network based content server to twoor more clients participating in a burst-based service session, themethod comprising:

-   -   following establishment of said session, joining the content        server to the session as a further participating client;    -   sending a media grant to the content server; and    -   delivering the requested media from the content server to the        other participating clients.

The invention is applicable in particular to distributing media from anetwork based content server to clients participating in a Push to talkOver cellular (PoC) session, according to PoC Release 1.0, 2.0, orfuture enhancements of the same protocols.

Preferably, said burst-based service session is established using theSession Initiation Protocol (SIP) signalling, and said content server isjoined to the session as a further participating client by sending a SIPINVITE to the content server. The SIP INVITE may be sent from acontrolling SIP Application Server as a result of that Server receivinga SIP REFER message from one of the participating clients. Morepreferably, the SIP REFER contains in the Refer-To header a SIP URIidentifying the content server.

The media requested may be identified by a URI parameter appended to theURI of the content server. Alternatively, the media may be identified inan “escaped” header field of the SIP REFER message.

Preferably, after the distribution of media from the content server hasbeen completed, the content server is removed from the ongoing session.Where SIP protocol is used to establish the session and add the contentserver as a participating client, the content server may be removed byone of the participating clients sending SIP REFER (BYE) request to thecontrolling server. Alternatively, the content server may remove itselfby sending a SIP BYE request to the controlling server.

According to a second aspect of the present invention there is provideda client terminal which is able to participate in a burst-based servicesession with one or more other client terminals, the terminalcomprising:

-   -   means for establishing a burst-based service session with one or        more other client terminals;    -   means for subsequently causing an invitation to the ongoing        session to be sent to a network based content server, the invite        identifying media to be shared with the participating client        terminals; and    -   means for receiving the identified media from the content server        after the content server has joined the session as a        participating client.

According to a third aspect of the present invention there is provided acontent server for use in distributing media to two or more clientsparticipating in an ongoing burst-based service session, the servercomprising:

-   -   means for joining the content server to the ongoing session as a        participating client; and    -   means for receiving a media grant from a controlling session        server; and    -   means for sending the requested media for delivery to the other        participating clients.

According to a fourth aspect of the present invention there is provideda method of distributing media from a network based content server totwo or more clients participating in a burst-based service sessioncontrolled by a session controlling server, the method comprising:

-   -   following establishment of said session, sending an HTTP request        from the session controlling server to the content server;    -   upon receipt of said request at the content server, identifying        media identified in the HTTP request; and    -   delivering the identified media from the content server to the        participating clients.

Preferably, said burst-based service session is established using theSession Initiation Protocol (SIP) signalling. The method comprises oneof the participating clients sending to said controlling server a MediaBurst request containing an HTTP URL identifying the content server. Inresponse to receipt of this message, the session controlling servergenerates and sends said HTTP request. The media identified by thecontent server is returned to the session controlling server whichdistributes the media to the participating clients.

According to a fifth aspect of the present invention there is provided asession controlling server for use in controlling a burst based servicesession involving two or more participating clients, the servercomprising:

-   -   means for establishing a session between two or more        participating clients;    -   means for receiving from one of said clients a Media Burst        request containing an HTTP URL identifying a content server at        which media is stored;    -   means for generating and sending to said content server an HTTP        request;    -   means for receiving media from said content server, and for        delivering the media to the participating clients.

According to a sixth aspect of the present invention there is provided auser terminal for use in a burst based service session involving one ormore other participating client terminals, the terminal comprising:

-   -   means for sending to a controlling server, a Media Burst request        containing an HTTP URL identifying a content server at which        media is stored, during an ongoing session with one or more        other participating client terminals; and    -   means for receiving media from said content server via said        controlling server.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a signal flow sequence according to a first embodiment ofthe invention; and

FIG. 2 shows a signal flow sequence according to a second embodiment ofthe invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The following discussion presents two solutions to the problem ofenabling a content server to distribute one or more media types to theparticipants in a Push-to-talk over Cellular (PoC) session. In order tofacilitate this media sharing, three main issues must be addressed:

How does the PoC Server understand that a user wants to share media?

How does the PoC User identify the media?

How does the PoC User instruct the content server what to share in thePoC Session.

A first approach involves adding the content server as a PoC Client tothe PoC Session, so that the content server is (temporarily) added tothe PoC Session. To illustrate this approach, consider an ongoing PoCsession between PoC Clients A and B, where each PoC Client has aparticipating PoC Server (PoC Servers A and B), and the session iscontrolled by a controlling PoC Server (PoC Server X). FIG. 1 shows themain SIP requests and SIP responses associated with this approach, wherethe PoC Release 1.0 names “Talk Burst Request”, “Talk Burst Idle”, etc.are changed to the generic names “Media Burst Request”, “Media BurstIdle”, etc. The message sequence is as follows:

PoC Client A sends a SIP REFER request in order to add (INVITE) thecontent server to the ongoing PoC Session. The SIP REFER requestincludes in the “Refer-To” header, the URI of the content server holdingthe media being requested. The media itself is also identified by aUniversal Resource Indicator (URI) parameter in the address of thecontent server or is identified within an “escaped” header field.

PoC Server X receives the SIP REFER request and as a consequence invitesthe PoC Content Server as if it was an ordinary PoC User using the SIPINVITE.

The Content server accepts the invitation and sends the SIP 200 OK(INVITE) response. The PoC Server X sends a SIP NOTIFY request to thePoC Client to indicate that the Content Server has accepted.

On receipt of the SIP NOTIFY request indicating that the content serverhas accepted the invitation, the PoC Client A can request permission tosend, for example, a picture on the behalf of the content server. Thisis done using the Media Burst Request message.

The PoC Server X grants the request and notifies both PoC Client A andthe content server (Media Burst Granted message), as well as PoC ClientB (Media Burst Taken message).

The content server sends the media to the PoC Server (Media Burst), andthe PoC Server X distributes the media to all participants that arecapable to receiving this type of media.

Once the media has been sent, the content server sends the Media BurstRelease message and the PoC Server distributes the information (MediaBurst Idle) that the floor is idle for this media type.

When the PoC Client A receives the Media Burst Idle message it can expelthe content server from the PoC session by means of a SIP REFER (BYE)request. An alternative means to achieve the same result is for thecontent server to leave the PoC Session by means of a SIP BYE request.

The solution illustrated in FIG. 1 has the advantage that neither thePoC Client nor the PoC Servers in the network need to identify that thecontent server is a PoC Client.

An alternative solution to the problem of enabling a content server todistribute one or more media types to the participants in a PoC sessionmakes use of an HTTP URL instead of a SIP address to identify the mediato be shared. Assume for example that a user has stored some media on acontent server or is surfing a round on the Internet and finds someinteresting media (e.g. a picture, an audio-clip, video-clip, etc.) thathe or she wants to share. FIG. 2 shows a simplified message flow forimplementing this approach. The message flow is as follows.

The PoC Client A sends a Media Burst Request message requestingpermission to send media (e.g. a picture) on behalf of another user. Theaddress of the other user is an HTTP URL, for example“http://my-content-op.net/user/˜u29502467/pictures/vacation05/kalle.jpg”.

When the PoC Server X receives the Media Burst Request messagecontaining the HTTP address (instead of a SIP URI), it sends an HTTP GETrequest to the content server.

The content server returns the file identified by the HTTP GET requestin the HTTP 200 “OK” response.

The PoC Server X sends a Media Burst Granted message to PoC Client A andMedia Burst Taken message to the PoC Client B and starts transmittingthe media (Media Burst).

Once the media has been distributed, the PoC Server X sends Media BurstIdle message to the participants (including the content server) toindicate that some one else may ask for permission to send media.

While the media sharing process is ongoing, one or other of the PoCUsers can ask the controlling PoC server X for permission to send a TalkBurst during which the PoC User at PoC Client A could talk about theshared picture with the PoC User at PoC Client B. This case is not shownin the example.

The alternative solution (of FIG. 2) has the advantage that thesignalling requirements are minimal. Another advantage is that thissolution can be used to share media stored on any PoC “unaware” webserver as long as the (controlling) PoC Server is authorized to fetchthe media. On the other hand, it can only be used to share media offinite size: It is not possible to use the solution, for example, toshare streaming video.

It will be appreciated by the person of skill in the art that variousmodifications may be made to the above described embodiments withoutdeparting from the scope of the present invention. For example, whilstthe invention has been illustrated above with reference to PoC, theinvention is applicable to other burst-type services such as, forexample, instant messaging services.

1. A method of distributing media from a network based content server totwo or more clients participating in a burst-based service session, themethod comprising: following establishment of said session, joining thecontent server to the session as a further participating client; sendinga media grant to the content server; and delivering the requested mediafrom the content server to the other participating clients.
 2. Themethod according to claim 1, wherein said burst-based service is Push totalk Over cellular.
 3. The method according to claim 1, wherein saidburst-based service session is established using Session InitiationProtocol (SIP) signaling, and said content server is joined to thesession as a further participating client by sending a SIP INVITE to thecontent server.
 4. The method according to claim 3, wherein the SIPINVITE is sent from a controlling SIP Application Server as a result ofthe Server receiving a SIP REFER message from one of the participatingclients.
 5. The method according to claim 4, wherein the SIP REFERmessage contains in a Refer-To header, a SIP URI identifying the contentserver.
 6. The method according to claim 5, wherein the media requestedis identified by a URI parameter appended to the URI of the contentserver.
 7. The method according to claim 5, wherein the media isidentified in an escaped header field of the SIP REFER message.
 8. Themethod according to claim 1, further comprising removing the contentserver from the ongoing session after the distribution of media from thecontent server has been completed.
 9. The method according to claim 8,wherein the burst-based service session is established using SIPsignaling and the content server is joined to the session as a furtherparticipating client by sending a SIP INVITE to the content server, andwherein the content server is removed by one of the participatingclients sending a SIP REFER (BYE) request to the controlling server. 10.The method according to claim 8, wherein the burst-based service sessionis established using SIP signaling and the content server is joined tothe session as a further participating client by sending a SIP INVITE tothe content server, and wherein the content server is removed by thecontent server sending a SIP BYE request to the controlling server. 11.A client terminal for participating in a burst-based service sessionwith one or more other client terminals, the client terminal comprising:means for establishing a burst-based service session with one or moreother client terminals; means for subsequently causing an invitation tothe ongoing session to be sent to a network based content server, theinvite identifying media to be shared with the participating clientterminals; and means for receiving the identified media from the contentserver after the content server has joined the session as aparticipating client.
 12. A content server for use in distributing mediato two or more clients participating in an ongoing burst-based servicesession, the content server comprising: means for joining the contentserver to the ongoing session as a participating client; means forreceiving a media grant from a controlling session server; and means forsending the requested media for delivery to the other participatingclients.
 13. A method of distributing media from a network based contentserver to two or more clients participating in a burst-based servicesession controlled by a session controlling server, the methodcomprising: following establishment of said session, sending an HTTPprotocol request from the session controlling server to the contentserver; upon receipt of said request at the content server, identifyingmedia identified in the HTTP request; and delivering the identifiedmedia from the content server to the participating clients.
 14. Themethod according to claim 13, wherein said burst-based service sessionis established using SIP signaling.
 15. The method according to claim13, further comprising the steps of: sending from one of theparticipating clients to said controlling server, a Media Burst requestcontaining an HTTP URL identifying the content server; and in responseto receipt of the Media Burst request, generating at the sessioncontrolling server said HTTP request and sending the HTTP request to thecontent server.
 16. The method according to claim 13, wherein said HTTPrequest is an HTTP GET.
 17. A session controlling server for use incontrolling a burst based service session involving two or moreparticipating clients, the server comprising: means for establishing asession between two or more participating clients; means for receivingfrom one of said clients a Media Burst request containing an HTTP URLidentifying a content server at which media is stored; means forgenerating and sending to said content server an HTTP request, means forreceiving media from said content server, and means for delivering themedia to the participating clients.
 18. A user terminal for use in aburst based service session involving one or more other participatingclient terminals, the user terminal comprising: means for sending to acontrolling server, during an ongoing session with one or more otherparticipating client terminals, a Media Burst request containing an HTTPURL identifying a content server at which media is stored; and means forreceiving media from said content server via said controlling server.